加筋土计算中等效附加应力法的改进

等效附加应力法的基本思路是把加筋土中筋的作用等效成外力加在土骨架上，取加筋土中的土体进行计算。这种方法能够适用于纤维加筋、分层加筋和土钉墙等不同情况，且能够克服一般复合材料方法中复合材料本构模型难以建立，和把筋土分开考虑的方法中接触面单元过多的弊病。但以前的等效附加应力法需要迭代计算，这给有限元编程带来困难，而且不利于已有程序的改编。对等效附加应力法进行改进，只要在原有土的弹性矩阵或弹塑性矩阵中加上一个附加矩阵就可以直接求解。这就使得不需要迭代就可以直接应用等效附加应力法进行加筋土计算，大大简化了编程难度，改进方法的提出有助于等效附加应力法的推广应用。

Modified equivalent additional stress method for numerical analysis of reinforced soil

The basic principle of equivalent additional stress method is that only soil skeleton is concerned while the reinforcing effect is considered to be equivalent additional stress acting on the soil skeleton in the direction reinforcement being bedded. This method is fit for fiber reinforced soil, soil nailing wall and soil reinforced with layered reinforcements, etc. It can not only remove interface element for the method dealing with soil and reinforcement separately, but also avoid determining the composite constitutive equation of the reinforced soil. However, iteration is necessary for the conventional equivalent additional stress method, which makes it difficult in writing FEM program. In this paper, a modified method is put forward to deal with this problem. An additional matrix is calculated and added to the elastic matrix or elastoplastic matrix of soil, the method can be employed directly without iteration. The modified method is easy for writing FEM program and helpful for extending the application of equivalent additional stress method.